Field of the Invention
The present invention relates to a process for separating off lower alkanols, mixtures of alkanols and water or water itself from oxygen-containing organic compounds from the group comprising higher alkanols and dialkyl carbonates. The separation is carried out by pervaporation or vapour permeation on a membrane which has been prepared by plasma polymerization.
The process according to the invention allows simplified separations, especially in those cases where distillative separation processes fail because of the presence of an azeotrope. This is of importance for many mixtures of various alkanols, in particular those also containing water, and for separation of dialkyl carbonates from the alcohols on which they are based, again also in those cases where a content of water is present, and for the separation of dialkyl carbonate from water itself. A very important industrial problem of this type is the separation of methanol from dimethyl carbonate, if appropriate in the presence of water contained in the mixture. Another important industrial problem of this type is the separation of water from dimethyl carbonate.